Legal sanctions do not appear to have a deterrent effect when looking at rates of hit-and-run pedestrian fatalities and sentencing guidelines for fatal hit-and-run crashes. For example, states with a maximum prison term of five years have a similar rate of hit-and-run pedestrian fatalities as states with a maximum prison term of 25 years. There is some evidence to suggest that harsher traffic safety laws may make the problem worse.

Counterintuitively, most hit-and-runs happen in the daytime in good conditions and on streets with lower speed limits, probably because that's when pedestrians and cyclists are more likely to be in the road. One study suggests that "in situations where the driver is not in control, such as when the weather is bad, they may not feel as responsible for the collision. Feeling less at fault for the crash may encourage drivers to stay at the scene."

Road design also matters; roads that are safer for pedestrians and cyclists have fewer crashes of any kind. But no matter how you look at it, there are more cars and more drivers out there, and a big rise in the number of deadly car crashes, killing more than 40,000 people last year.

Another potential factor Mr. [AAA Director of Safety Jake] Nelson cited is the push by public health officials to encourage people to walk and bike more. The downside, he said, is those activities make people more vulnerable in the event of a crash involving a car or truck. The number of bike commuters nationwide has ebbed in recent years, but rose nearly 40% from 2006 to 2016, when 864,000 rode to work, according to the Census Bureau.

To improve safety, he said, pedestrians and cyclists need physical barriers like protected bike lanes—an idea gaining popularity around the U.S. but also causing fights in some places over reduced parking or travel lanes.

I live in Toronto, Canada, where last week a man used a truck to kill 10 people on the sidewalk because he was mad at women. A recent redesign for the street where this happened proposed reducing the road from six lanes to four and putting in bike lanes but the Mayor of the City is against it because taking out the lanes might slow down traffic.

At the time, I was walking and cycling on Hornby Street in Vancouver, which has concrete planters protecting the cycle lane, which also protects the sidewalk.

And I wondered what kind of person puts a minute or two's driving time ahead of the protection of cyclists and pedestrians, who also are less likely to be killed crossing the streets when there are fewer lanes and a shorter distance. Even before this tragedy the number of pedestrians killed by cars was already appalling.

Perhaps in the light of the increasing numbers of pedestrians and cyclists in the roads, the increasing number of fatalities, and the newfound popularity of trucks as weapons, it is time to reconsider our urban road designs and make protected bike lanes the new normal on busy streets.